The aims of the proposed research program are (a) to develop mathematical models describing the mechanical behaviour of ventricular and aortic aneurysms. (b) extend the rheological models of isolated heart muscle to the intact heart. (c) study the anisotropic elastic behaviour of arteries. (d) develop indices of cardiac function for use in patients with coronary artery disease and severe regurgitant lesions. (e) analyze the frequency content of the first and third heart sounds and thus evaluate the effective elastic modulus of the ventricle. The mathematical models to be studied in parts (a)-(c) are based on the three dimensional equations of elasticity. Parts (a) and (b) are expected to provide a better understanding of the mechanics and performance of normal, hypertrophied and infarcted ventricles. Some insight to the aging process, arteriosclerosis and hypertension should result from the studies in part (c). The clinical aspects of assessing cardiac function outlined in parts (d) and (e) involve the use of the direct methods (cineangiographic analysis and measurement of left ventricular pressure) and the indirect methods (apexcardiogram, carotid pulse tracings and phonocardiograms). Infant and adult data will be made available for these studies.